The present invention relates to heat exchange devices and more particularly to heat exchange devices for recapturing heat normally lost from a wood burning stove or the like for use in heating ambient air of an enclosed space.
In the prior art there are a number of devices shown for recovering heat from a surface of a wood stove or similar heat source. However, each of the prior art devices of which the inventor is aware have one or more disadvantages which are not present with the instant invention.
U.S. Pat. No. 97,678 shows a heater attachment for stoves or ranges adapted to receiving the heat from the top of the stove to heat other rooms in a building.
The attachment shown in the patent does not provide a heat exchange device which extends into the fire box of the stove nor does the patented device include a blower for moving the heated air nor handle for ease of handling the heat exchange device.
U.S. Pat. No. 472,755 shows a heat exchange device constructed of cast iron with an air tight bottom portion which fits into a recess of a stove. Heat is transmitted either through a hot air pipe to another floor of a building or through one or more valves into the room in which the stove is located.
The device according to the patent does not provide any means for moving a large quantity of ambient air through a heat exchange device nor does the patented device include any baffle or heat exchange tube for increasing the area within the heat exchanger for enhancing the efficiency of heating ambient air as it passes through the device.
U.S. Pat. No. 2,553,278 shows a hood device which is mounted over a number of gas burners on a stove including a blower and a number of exit ports for transmitting heat captured under the hood device to the ambient air surrounding the stove.
The apparatus according to the patent does not include means for exchanging heat which means extend into the fire box nor does the hood arrangement of the patent show any heat exchange tubes or baffles for increasing the efficiency of the heat exchange within the system.
U.S. Pat. No. 3,533,466 shows a tubular heat exchanger for use in cooling combustion gases of a refuse incinerator by means of cold air. A number of vertical steel tubes are provided for the upward passage of the combustion gases which are mounted within a casing. Cooling air is supplied in two streams flowing crosswise with respect to the verticle tubes. The volume of one of the air streams is controlled in dependence upon the outlet temperature of the cooled combustion gases.
The patented heat exchanger is fundamentally an in line device in which exhaust gases from the heat source pass through the steel tubes. This system is distinct from a system in which a heat exchanger extends into the fire box and collects heated air within a main cavity of a heat exchange device but wherein the exhaust gases from the heat source do not pass through the heat exchange device as is shown by the patent.
U.S. Pat. No. 4,050,628 also shows an apparatus for reclaiming heat and for controlling the flow of combustion gases passing through a flue from a heater to an exhaust stack. As with the patent identified immediately above, the heat reclaimer according to the identified patent employs exhaust gases passing through the heat exchange device to provide the heat for heating ambient air. This patent does not show a heat exchange device extending into the fire box of the heat source. Also, the device according to the patent does not show means for moving a large volume of air through the heat exchanger to provide adequate heat to heat a room or other enclosed space.
U.S. Pat. No. 4,206,742 shows apparatus for extracting heat from exhaust gases of a stove to heat the air in a room. A heat exchange chamber includes an inner core having a number of passageways through which waste gases pass. The air surrounding the inner core is heated by the passage of the exhaust gases which then exit into the flue.
As with other patented devices which are mounted in line with the exhaust gases from the heat source, heat is recovered from exhaust gases which pass through the heat extractor.
U.S. Pat. No. 4,213,443 shows a rectangular stove structure having a step top with a sloped intermediate top portion having heated air outlets. Room air is passed through U-shaped ducts arranged along the inside surface of the side walls of the stove and fire brick is provided on the floor of the stove structure between the ducts. Air is drawn into the ducts through a side opening having a blower associated therewith.
The patent relates to a stove structure including means within the fire box for heating ambient air. The patent does not show a device for mounting on a top surface of a stove structure with heat exchange means extending into the fire box, a blower for moving heated ambient air through the heat exchanger and a number of sealed heat exchange tubes for transmitting heat to ambient air in an efficient manner.
U.S. Pat. No. 4,219,073 shows a heat exchanger which is adapted to be mounted in an exhaust stack of an oil or natural gas furnace including a heat exchange chamber with a plurality of separate closely packed tubular conduits arranged to transport hot exhaust gases there through, a fan assembly attached to a side wall to force ambient air around the plurality of tubular contuits to heat the ambient air and a thermostat extending into the ambient air passageway for monitoring the ambient air temperature and selectively actuating the fan assembly at pre-set temperatures.
As with the patents identified above, the patented structure is designed to be mounted in an exhaust stack and have exhaust gases pass through the tubular conduits. The patented device is not adapted to be mounted on a top surface of a stove with a heat exchanger which extends into the fire box nor does it have tubular heat exchange members which are sealed at one end thereof for providing efficient transfer of heat energy to ambient air which is forced through the heat exchanger by a blower.
Each of the prior art devices discussed has one or more disadvantages which compared to the instant invention as will be seen from the following summary of the invention.